// ASM: a very small and fast Java bytecode manipulation framework
// Copyright (c) 2000-2011 INRIA, France Telecom
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//
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// modification, are permitted provided that the following conditions
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package org.springframework.asm;

/**
 * A reference to a type appearing in a class, field or method declaration, or on an instruction.
 * Such a reference designates the part of the class where the referenced type is appearing (e.g. an
 * 'extends', 'implements' or 'throws' clause, a 'new' instruction, a 'catch' clause, a type cast, a
 * local variable declaration, etc).
 *
 * @author Eric Bruneton
 */
public class TypeReference {

	/**
	 * The sort of type references that target a type parameter of a generic class. See {@link
	 * #getSort}.
	 */
	public static final int CLASS_TYPE_PARAMETER = 0x00;

	/**
	 * The sort of type references that target a type parameter of a generic method. See {@link
	 * #getSort}.
	 */
	public static final int METHOD_TYPE_PARAMETER = 0x01;

	/**
	 * The sort of type references that target the super class of a class or one of the interfaces it
	 * implements. See {@link #getSort}.
	 */
	public static final int CLASS_EXTENDS = 0x10;

	/**
	 * The sort of type references that target a bound of a type parameter of a generic class. See
	 * {@link #getSort}.
	 */
	public static final int CLASS_TYPE_PARAMETER_BOUND = 0x11;

	/**
	 * The sort of type references that target a bound of a type parameter of a generic method. See
	 * {@link #getSort}.
	 */
	public static final int METHOD_TYPE_PARAMETER_BOUND = 0x12;

	/**
	 * The sort of type references that target the type of a field. See {@link #getSort}.
	 */
	public static final int FIELD = 0x13;

	/**
	 * The sort of type references that target the return type of a method. See {@link #getSort}.
	 */
	public static final int METHOD_RETURN = 0x14;

	/**
	 * The sort of type references that target the receiver type of a method. See {@link #getSort}.
	 */
	public static final int METHOD_RECEIVER = 0x15;

	/**
	 * The sort of type references that target the type of a formal parameter of a method. See {@link
	 * #getSort}.
	 */
	public static final int METHOD_FORMAL_PARAMETER = 0x16;

	/**
	 * The sort of type references that target the type of an exception declared in the throws clause
	 * of a method. See {@link #getSort}.
	 */
	public static final int THROWS = 0x17;

	/**
	 * The sort of type references that target the type of a local variable in a method. See {@link
	 * #getSort}.
	 */
	public static final int LOCAL_VARIABLE = 0x40;

	/**
	 * The sort of type references that target the type of a resource variable in a method. See {@link
	 * #getSort}.
	 */
	public static final int RESOURCE_VARIABLE = 0x41;

	/**
	 * The sort of type references that target the type of the exception of a 'catch' clause in a
	 * method. See {@link #getSort}.
	 */
	public static final int EXCEPTION_PARAMETER = 0x42;

	/**
	 * The sort of type references that target the type declared in an 'instanceof' instruction. See
	 * {@link #getSort}.
	 */
	public static final int INSTANCEOF = 0x43;

	/**
	 * The sort of type references that target the type of the object created by a 'new' instruction.
	 * See {@link #getSort}.
	 */
	public static final int NEW = 0x44;

	/**
	 * The sort of type references that target the receiver type of a constructor reference. See
	 * {@link #getSort}.
	 */
	public static final int CONSTRUCTOR_REFERENCE = 0x45;

	/**
	 * The sort of type references that target the receiver type of a method reference. See {@link
	 * #getSort}.
	 */
	public static final int METHOD_REFERENCE = 0x46;

	/**
	 * The sort of type references that target the type declared in an explicit or implicit cast
	 * instruction. See {@link #getSort}.
	 */
	public static final int CAST = 0x47;

	/**
	 * The sort of type references that target a type parameter of a generic constructor in a
	 * constructor call. See {@link #getSort}.
	 */
	public static final int CONSTRUCTOR_INVOCATION_TYPE_ARGUMENT = 0x48;

	/**
	 * The sort of type references that target a type parameter of a generic method in a method call.
	 * See {@link #getSort}.
	 */
	public static final int METHOD_INVOCATION_TYPE_ARGUMENT = 0x49;

	/**
	 * The sort of type references that target a type parameter of a generic constructor in a
	 * constructor reference. See {@link #getSort}.
	 */
	public static final int CONSTRUCTOR_REFERENCE_TYPE_ARGUMENT = 0x4A;

	/**
	 * The sort of type references that target a type parameter of a generic method in a method
	 * reference. See {@link #getSort}.
	 */
	public static final int METHOD_REFERENCE_TYPE_ARGUMENT = 0x4B;

	/**
	 * The target_type and target_info structures - as defined in the Java Virtual Machine
	 * Specification (JVMS) - corresponding to this type reference. target_type uses one byte, and all
	 * the target_info union fields use up to 3 bytes (except localvar_target, handled with the
	 * specific method {@link MethodVisitor#visitLocalVariableAnnotation}). Thus, both structures can
	 * be stored in an int.
	 *
	 * <p>This int field stores target_type (called the TypeReference 'sort' in the public API of this
	 * class) in its most significant byte, followed by the target_info fields. Depending on
	 * target_type, 1, 2 or even 3 least significant bytes of this field are unused. target_info
	 * fields which reference bytecode offsets are set to 0 (these offsets are ignored in ClassReader,
	 * and recomputed in MethodWriter).
	 *
	 * @see <a href="https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.20">JVMS
	 * 4.7.20</a>
	 * @see <a
	 * href="https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.20.1">JVMS
	 * 4.7.20.1</a>
	 */
	private final int targetTypeAndInfo;

	/**
	 * Constructs a new TypeReference.
	 *
	 * @param typeRef the int encoded value of the type reference, as received in a visit method
	 *                related to type annotations, such as {@link ClassVisitor#visitTypeAnnotation}.
	 */
	public TypeReference(final int typeRef) {
		this.targetTypeAndInfo = typeRef;
	}

	/**
	 * Returns a type reference of the given sort.
	 *
	 * @param sort one of {@link #FIELD}, {@link #METHOD_RETURN}, {@link #METHOD_RECEIVER}, {@link
	 *             #LOCAL_VARIABLE}, {@link #RESOURCE_VARIABLE}, {@link #INSTANCEOF}, {@link #NEW}, {@link
	 *             #CONSTRUCTOR_REFERENCE}, or {@link #METHOD_REFERENCE}.
	 * @return a type reference of the given sort.
	 */
	public static TypeReference newTypeReference(final int sort) {
		return new TypeReference(sort << 24);
	}

	/**
	 * Returns a reference to a type parameter of a generic class or method.
	 *
	 * @param sort       one of {@link #CLASS_TYPE_PARAMETER} or {@link #METHOD_TYPE_PARAMETER}.
	 * @param paramIndex the type parameter index.
	 * @return a reference to the given generic class or method type parameter.
	 */
	public static TypeReference newTypeParameterReference(final int sort, final int paramIndex) {
		return new TypeReference((sort << 24) | (paramIndex << 16));
	}

	/**
	 * Returns a reference to a type parameter bound of a generic class or method.
	 *
	 * @param sort       one of {@link #CLASS_TYPE_PARAMETER} or {@link #METHOD_TYPE_PARAMETER}.
	 * @param paramIndex the type parameter index.
	 * @param boundIndex the type bound index within the above type parameters.
	 * @return a reference to the given generic class or method type parameter bound.
	 */
	public static TypeReference newTypeParameterBoundReference(
			final int sort, final int paramIndex, final int boundIndex) {
		return new TypeReference((sort << 24) | (paramIndex << 16) | (boundIndex << 8));
	}

	/**
	 * Returns a reference to the super class or to an interface of the 'implements' clause of a
	 * class.
	 *
	 * @param itfIndex the index of an interface in the 'implements' clause of a class, or -1 to
	 *                 reference the super class of the class.
	 * @return a reference to the given super type of a class.
	 */
	public static TypeReference newSuperTypeReference(final int itfIndex) {
		return new TypeReference((CLASS_EXTENDS << 24) | ((itfIndex & 0xFFFF) << 8));
	}

	/**
	 * Returns a reference to the type of a formal parameter of a method.
	 *
	 * @param paramIndex the formal parameter index.
	 * @return a reference to the type of the given method formal parameter.
	 */
	public static TypeReference newFormalParameterReference(final int paramIndex) {
		return new TypeReference((METHOD_FORMAL_PARAMETER << 24) | (paramIndex << 16));
	}

	/**
	 * Returns a reference to the type of an exception, in a 'throws' clause of a method.
	 *
	 * @param exceptionIndex the index of an exception in a 'throws' clause of a method.
	 * @return a reference to the type of the given exception.
	 */
	public static TypeReference newExceptionReference(final int exceptionIndex) {
		return new TypeReference((THROWS << 24) | (exceptionIndex << 8));
	}

	/**
	 * Returns a reference to the type of the exception declared in a 'catch' clause of a method.
	 *
	 * @param tryCatchBlockIndex the index of a try catch block (using the order in which they are
	 *                           visited with visitTryCatchBlock).
	 * @return a reference to the type of the given exception.
	 */
	public static TypeReference newTryCatchReference(final int tryCatchBlockIndex) {
		return new TypeReference((EXCEPTION_PARAMETER << 24) | (tryCatchBlockIndex << 8));
	}

	/**
	 * Returns a reference to the type of a type argument in a constructor or method call or
	 * reference.
	 *
	 * @param sort     one of {@link #CAST}, {@link #CONSTRUCTOR_INVOCATION_TYPE_ARGUMENT}, {@link
	 *                 #METHOD_INVOCATION_TYPE_ARGUMENT}, {@link #CONSTRUCTOR_REFERENCE_TYPE_ARGUMENT}, or {@link
	 *                 #METHOD_REFERENCE_TYPE_ARGUMENT}.
	 * @param argIndex the type argument index.
	 * @return a reference to the type of the given type argument.
	 */
	public static TypeReference newTypeArgumentReference(final int sort, final int argIndex) {
		return new TypeReference((sort << 24) | argIndex);
	}

	/**
	 * Returns the sort of this type reference.
	 *
	 * @return one of {@link #CLASS_TYPE_PARAMETER}, {@link #METHOD_TYPE_PARAMETER}, {@link
	 * #CLASS_EXTENDS}, {@link #CLASS_TYPE_PARAMETER_BOUND}, {@link #METHOD_TYPE_PARAMETER_BOUND},
	 * {@link #FIELD}, {@link #METHOD_RETURN}, {@link #METHOD_RECEIVER}, {@link
	 * #METHOD_FORMAL_PARAMETER}, {@link #THROWS}, {@link #LOCAL_VARIABLE}, {@link
	 * #RESOURCE_VARIABLE}, {@link #EXCEPTION_PARAMETER}, {@link #INSTANCEOF}, {@link #NEW},
	 * {@link #CONSTRUCTOR_REFERENCE}, {@link #METHOD_REFERENCE}, {@link #CAST}, {@link
	 * #CONSTRUCTOR_INVOCATION_TYPE_ARGUMENT}, {@link #METHOD_INVOCATION_TYPE_ARGUMENT}, {@link
	 * #CONSTRUCTOR_REFERENCE_TYPE_ARGUMENT}, or {@link #METHOD_REFERENCE_TYPE_ARGUMENT}.
	 */
	public int getSort() {
		return targetTypeAndInfo >>> 24;
	}

	/**
	 * Returns the index of the type parameter referenced by this type reference. This method must
	 * only be used for type references whose sort is {@link #CLASS_TYPE_PARAMETER}, {@link
	 * #METHOD_TYPE_PARAMETER}, {@link #CLASS_TYPE_PARAMETER_BOUND} or {@link
	 * #METHOD_TYPE_PARAMETER_BOUND}.
	 *
	 * @return a type parameter index.
	 */
	public int getTypeParameterIndex() {
		return (targetTypeAndInfo & 0x00FF0000) >> 16;
	}

	/**
	 * Returns the index of the type parameter bound, within the type parameter {@link
	 * #getTypeParameterIndex}, referenced by this type reference. This method must only be used for
	 * type references whose sort is {@link #CLASS_TYPE_PARAMETER_BOUND} or {@link
	 * #METHOD_TYPE_PARAMETER_BOUND}.
	 *
	 * @return a type parameter bound index.
	 */
	public int getTypeParameterBoundIndex() {
		return (targetTypeAndInfo & 0x0000FF00) >> 8;
	}

	/**
	 * Returns the index of the "super type" of a class that is referenced by this type reference.
	 * This method must only be used for type references whose sort is {@link #CLASS_EXTENDS}.
	 *
	 * @return the index of an interface in the 'implements' clause of a class, or -1 if this type
	 * reference references the type of the super class.
	 */
	public int getSuperTypeIndex() {
		return (short) ((targetTypeAndInfo & 0x00FFFF00) >> 8);
	}

	/**
	 * Returns the index of the formal parameter whose type is referenced by this type reference. This
	 * method must only be used for type references whose sort is {@link #METHOD_FORMAL_PARAMETER}.
	 *
	 * @return a formal parameter index.
	 */
	public int getFormalParameterIndex() {
		return (targetTypeAndInfo & 0x00FF0000) >> 16;
	}

	/**
	 * Returns the index of the exception, in a 'throws' clause of a method, whose type is referenced
	 * by this type reference. This method must only be used for type references whose sort is {@link
	 * #THROWS}.
	 *
	 * @return the index of an exception in the 'throws' clause of a method.
	 */
	public int getExceptionIndex() {
		return (targetTypeAndInfo & 0x00FFFF00) >> 8;
	}

	/**
	 * Returns the index of the try catch block (using the order in which they are visited with
	 * visitTryCatchBlock), whose 'catch' type is referenced by this type reference. This method must
	 * only be used for type references whose sort is {@link #EXCEPTION_PARAMETER} .
	 *
	 * @return the index of an exception in the 'throws' clause of a method.
	 */
	public int getTryCatchBlockIndex() {
		return (targetTypeAndInfo & 0x00FFFF00) >> 8;
	}

	/**
	 * Returns the index of the type argument referenced by this type reference. This method must only
	 * be used for type references whose sort is {@link #CAST}, {@link
	 * #CONSTRUCTOR_INVOCATION_TYPE_ARGUMENT}, {@link #METHOD_INVOCATION_TYPE_ARGUMENT}, {@link
	 * #CONSTRUCTOR_REFERENCE_TYPE_ARGUMENT}, or {@link #METHOD_REFERENCE_TYPE_ARGUMENT}.
	 *
	 * @return a type parameter index.
	 */
	public int getTypeArgumentIndex() {
		return targetTypeAndInfo & 0xFF;
	}

	/**
	 * Returns the int encoded value of this type reference, suitable for use in visit methods related
	 * to type annotations, like visitTypeAnnotation.
	 *
	 * @return the int encoded value of this type reference.
	 */
	public int getValue() {
		return targetTypeAndInfo;
	}

	/**
	 * Puts the given target_type and target_info JVMS structures into the given ByteVector.
	 *
	 * @param targetTypeAndInfo a target_type and a target_info structures encoded as in {@link
	 *                          #targetTypeAndInfo}. LOCAL_VARIABLE and RESOURCE_VARIABLE target types are not supported.
	 * @param output            where the type reference must be put.
	 */
	static void putTarget(final int targetTypeAndInfo, final ByteVector output) {
		switch (targetTypeAndInfo >>> 24) {
			case CLASS_TYPE_PARAMETER:
			case METHOD_TYPE_PARAMETER:
			case METHOD_FORMAL_PARAMETER:
				output.putShort(targetTypeAndInfo >>> 16);
				break;
			case FIELD:
			case METHOD_RETURN:
			case METHOD_RECEIVER:
				output.putByte(targetTypeAndInfo >>> 24);
				break;
			case CAST:
			case CONSTRUCTOR_INVOCATION_TYPE_ARGUMENT:
			case METHOD_INVOCATION_TYPE_ARGUMENT:
			case CONSTRUCTOR_REFERENCE_TYPE_ARGUMENT:
			case METHOD_REFERENCE_TYPE_ARGUMENT:
				output.putInt(targetTypeAndInfo);
				break;
			case CLASS_EXTENDS:
			case CLASS_TYPE_PARAMETER_BOUND:
			case METHOD_TYPE_PARAMETER_BOUND:
			case THROWS:
			case EXCEPTION_PARAMETER:
			case INSTANCEOF:
			case NEW:
			case CONSTRUCTOR_REFERENCE:
			case METHOD_REFERENCE:
				output.put12(targetTypeAndInfo >>> 24, (targetTypeAndInfo & 0xFFFF00) >> 8);
				break;
			default:
				throw new IllegalArgumentException();
		}
	}
}
